Electronic devices dissipate heat during operation. Thermal management refers to the ability to keep temperature-sensitive elements in an electronic device within a prescribed operating temperature. Thermal management has evolved to address the increased temperatures created within such electronic devices as a result of increased processing speed/power of the electronic devices. Historically, electronic devices were cooled by a natural convection thermal management technique. That is, the cases or packaging of these prior art electronic devices were designed with openings (e.g., slots) strategically located to allow warm air to escape and cooler air to be drawn in.
However, with the advent of high performance processors such as the Intel Itanium® processor, electronic devices have required more innovative thermal management. For example, in the last several years processing speeds of computer systems have climbed from 25 MHZ to over 1000 MHZ. Each of these increases in processing speed and power generally carry with it a “cost” of increased heat dissipation. Corresponding improvements in thermal management technology accompanied, out of necessity, such technological improvements. Natural convection was no longer sufficient to provide proper thermal management.
Several methods have been employed for cooling high performance electronic devices such as processors. A common method of cooling such a processor is by the use of a fan heat sink. FIG. 1A is a diagram of a prior art fan heat sink 100. As shown in FIG. 1A, an axial fan 102 is attached by a fan holder 104 to a heat sink 106 atop a processor. The fan heat sink 100 blows air across the heat sink 106 to remove the heat dissipated by the processor. To date, the best fan heat sinks are not thermally efficient enough to cool the new higher powered processors. One reason that previous fan heat sinks are not thermally efficient is that the fan forces air down on the processor. One problem with a fan that is positioned atop a heat sink, such as in FIG. 1A, is that the fan is too closely located to the fins of the heat sink to generate fully developed air flow. There is a dead space in the air flow which is caused by the fan hub. A fan heat sink such as the fan heat sink shown in FIG. 1A is not capable of providing fully developed air flow.
Another approach to cooling high performance processors is the use of passive heat sinks in combination with an axial system fan. One of the problems with the use of a large system fan is blowby. As used herein, the term “blowby” refers to air that is moved by a fan, but does not pass through the fins of a heat sink or over the electronic component itself. For example, when a large system fan is used in conjunction with a heat sink to cool an electronic component, a large percentage of the air moved by the system fan does not go through the heat sink. As a result, large system fans are not an efficient thermal solution for cooling a specific electronic component. Furthermore, some of these new high performance systems require multiple fans to maintain proper operating temperatures. However, the additional fans necessary for previous forced-air cooling systems result not only in an added expense for manufacturers of such electronic devices, but are often bulky and require an inordinate amount of real estate within the chassis. Another problem with the use of multiple system fans is the noise generated by the fans.
In recent years, power dissipation from components in a computer system chassis has increased in small increments for most computer system components except for processors. FIG. 1B is a bar graph comparing the power dissipation for various computer system components designed in 1999 and 2000. As shown in FIG. 1B, power dissipation for hard drives, memory, and chipsets designed in 2000 increased by only a few watts compared to similar components designed in 1999. Yet, even for computer systems designed in 2000, the power dissipation for each of the following is still under 20 Watts: hard drives, memory, chipsets and add-in cards. However, the power dissipated by a high performance processor has nearly doubled between 1999 and 2000 (as indicated by the arrow 108 in FIG. 1B). For example, in 1999 the power dissipation for a processor was generally between 30 and 40 watts. However, the power dissipation for some high performance processors currently being designed is as much as 70 watts. As shown in FIG. 1B, the power dissipation from processors has increased by about 30 watts in a one year period. Furthermore, it is anticipated that in future years the power dissipation of processors will increase even more dramatically.
The cooling systems currently being used, such as fan heat sinks and large system fans as described above, are not sufficient to effectively cool such high performance processors. What is needed is a thermal solution to provide high performance cooling for particular electronic components with disproportionately higher power dissipation.
For these and other reasons, there is a need for a heat dissipation device to efficiently dissipate the heat generated by high performance electronic devices.